A traffic control system is composed of, for example, a central apparatus located in a traffic control center, and traffic signal controllers, vehicle detectors, information boards, traffic monitor terminals, etc. which communicate with the central apparatus via a dedicated communication line (refer to Patent Literature 1, for example).
In this traffic control system, a traffic index of a predetermined road section is calculated on the basis of, for example, detection signals from vehicle detectors installed at appropriate locations in an area to be controlled, and traffic-actuated control such as setting of optimum traffic light switching timings for a plurality of intersections is performed on the basis of the calculated traffic index.
Meanwhile, a technique is also proposed in which a roadside communication apparatus installed at an intersection receives probe information that is wirelessly transmitted/received in vehicle-to-vehicle communication, and relays the probe information to a central apparatus, whereby the probe information generated by vehicles can be used for traffic-actuated control performed by the central apparatus in a traffic control center (refer to Patent Literature 2, for example).